Portable telephone



FIG. 1 is a front, top, and left side perspective view showing our new design for a portable telephone with broken line matter being for illustrative purposes only and forming no part of the claimed design;

FIG. 2 is a right side elevation view thereof.

FIG. 3 is a rear elevation view thereof; and,

FIG. 4 is a top plan view thereof. 

The ornamental design for a portable telephone, as shown and described. 